The present invention relates to a device for the UV treatment of flowing media, in particular to a device for the UV disinfection of drinking water or waste water.
Generic devices are known from the practice, for example from documents U.S. Pat. No. 5,368,826, U.S. Pat. No. 5,660,719, EP 068 7201 and WO 00/40511.
The general technical background of the present invention relates to UV disinfection systems. A distinction must firstly be drawn between UV disinfection systems comprising medium-pressure emitters, which are not the subject of the present invention, and systems of this type comprising low-pressure mercury UV emitters. The systems comprising medium-pressure emitters conventionally have few emitter units, which are distinguished by high UV radiation power with correspondingly increased electrical power consumption. As there are, in this case, only a few emitters, separate monitoring of each individual emitter is easily possible. In the case of medium-pressure emitters, the cost of this monitoring is low compared to other expenses and equipment costs.
A significantly larger number of emitters are used in systems comprising low-pressure emitters. Although these emitters respectively have lower UV radiation power, they require lower equipment costs than medium-pressure emitters and are also substantially more efficient, thus reducing operating costs. In some cases, systems of this type therefore comprise several hundred emitters, which are arranged as what is known as an array in one or more flow channels. These emitters are conventionally used and operated jointly when they are new. The service life of emitters of this type is approximately 8,000 to 9,000 operating hours, i.e. about one year. After this time, the radiation power has decreased to the extent that the emitters have to be exchanged. The emitted radiation power is monitored by UV sensors, which monitor either the entire array or individual selected modules or groups of the array, as in the abovementioned documents U.S. Pat. No. 5,368,826, EP 068 7201 and WO 00/40511. These documents do not make provision for individual monitoring of all of the emitters. In practice, it is assumed that all of the emitters age uniformly.
U.S. Pat. No. 5,660,719 proposes one approach for monitoring individual emitters. In this device, a coil, which receives from the power supply the electromagnetic radiation of the emitter in operation and which is then separately evaluated, is allocated to each lamp. The emitted radiation intensity itself is also in this document measured via a single UV sensor for a plurality of emitters, so the intensity signal is provided only for the overall array, while the information from the operating voltage is provided for each individual lamp.
However, monitoring of the individual radiation power of each individual emitter is therefore possible only indirectly, as the supply voltage path does not provide a clear indication of the emitted UV radiation. It is therefore conceivable, for example, that, in the case of an electrical emitter, which is entirely intact from the point of view of gas inflation, the emitter tube or the cladding tube surrounding the emitter has only limited UV transparency and there is therefore less UV radiation available than is assumed according to the electrical parameters.
The object of the present invention is therefore to provide a device for the UV treatment of flowing media, in which the radiation power of many low-pressure mercury emitters is individually monitored.